This invention relates in general to material crushers and, in particular, to a new and useful horizontal-type single toggle jaw breaker for crushing medium to large size materials, particularly coal and other minerals, on the upper strand or reach of a conveyor, preferably a chain scraper conveyor, which has a stationary breaking jaw and a breaking jaw swinging horizontally about a vertical axis of rotation over the upper strand, which is supported in the range of the end of its axis of rotation by means of toggle joints, and connected with its working end to an eccentric drive including a driving motor, a transmission, an eccentric shaft and a crank shaft as an energy accumulator.